Hennessey announced its plans for upgraded variants of the 2020 Corvette a few weeks ago. We approached the Texas-based tuner with some skepticism in our coverage, seeing as there wasn’t much information available on how Hennessey planned to reach the outrageous power levels it claimed. We reached out to Hennessey in the process of researching the story but did not receive any answers in time for publication, but since then Hennessey reached out and offered some answers. So let’s dive in.
To recap, Hennessey expects its supercharger kit to offer around 700 horsepower at a price of $25,000, while the twin-turbo kit will offer upwards of 1200 horsepower at a cost of more than $75,000 installed. (One of the first questions that we asked was why Hennessey is focusing on turbocharging now, given that most of the tuner’s previous Corvette kits were supercharged. Unfortunately, Hennessey did not provide a clear answer.) Tuning of the E99 ECU, which is used in the new Corvette, has been a bit of an uphill process so we wanted to know if Hennessey had plans to modify that ECU or use something new. Hennessey responded that it will tune the factory E99 ECU with HP Tuners software when the option becomes available, but that the company is considering other avenues, as well. With regard to the tune itself, a representative had this to say:
“We also hear that GM may offer its own tuning program and we would be happy to use their software as well. No one knows when C8 tuning software will become available but we are hopeful that this will be available sometime before the end of 2020. In the meantime, we expect to receive our first C8 in March or April and we will be busy mocking up our first supercharger and twin-turbo systems while we await tuning software.”
Hennessey states that it does do not foresee any challenges on tuning the LT2 engine. Its analysis shows that the LT2 engine is nearly identical to the LT1, with the exception of the dry-sump oiling system and the tubular exhaust manifolds. Hennessey stresses that it tuned over 500 examples of the LT-series engines over the past several years and plan to use that experience to be able to modify the LT2. These are conclusions based on visual examination of the engine; the company does not yet have an LT2 on hand but expects the 2020 Corvette it purchased to arrive sometime this spring.
One of our big questions is how Hennessey expects to support 1200 horsepower with the stock fuel system in the Corvette. Answer? For the twin-turbo upgrade, this version of the Hennessey tune will use E85 ethanol, with the possibility of some additional fuel system upgrades if necessary.
The dual-clutch transmission in the Corvette is a brand-new unit from Tremec, so there are not any performance transmission shops that have yet had the chance to tinker with one. Given that situation, we were surprised that Hennessey announced upgrades for the unit and wanted to know more. Remember, the company doesn’t have a C8 in hand yet, which means they have not actually examined the unit up close. Hennessey does, however, have a game plan in mind.
Hennessey’s goal for the DCT is to work with one of its current vendors that upgrades gearboxes for the Nissan GT-R, Audi R8, and Lamborghini Huracán. That’s the type of expertise needed to handle more than 1000 horsepower. “We will see soon enough,” a Hennessey representative told us. “Most likely we will have to upgrade clutches and maybe other DCT internal parts. Depends on how the customer is going to drive the car. On the street with street tires is less strenuous, but for customers who want to run down a sticky drag strip with sticky tires—that may require more upgrade work in the transmission.”
Tremec has not given Hennessey access to the new 32-bit control unit, which means so far the tuner has not found a way to tune it. Still, Hennessey’s practice is to start with the powertrain as it is delivered from the factory, so the process can formally begin once the C8 is in hand this spring. (Remember, production was delayed because of the UAW strikes last fall.) John Hennessey also adds the following on his namesake outfit’s approach to the upgrades and use of the factory Tremec TR-9080 gearbox:
“Ideally, we design our upgrades to work in concert with the factory-designed systems for maximum performance and reliability. In some rare cases we may do away with the factory design and create our own but this can be very time-consuming and expensive. It’s far easier and better for the customer and our business to ‘make the wheel roll smoother and more efficiently’ rather than ‘invent a new wheel.’ Historically, GM builds its engines, transmissions and driveline systems to handle a lot more power than its cars are delivered with from the factory. We hope and expect the same will be true on the C8. We will find out soon enough.”
These answers do help to shed a bit more light Hennessey’s tuning strategy for the new Corvette, but the company’s projections are ultimately based on the results from the previous-generation Corvette. More concrete estimates will be available once Hennessey can dig into a real C8 in its Texas shop. Once that happens, we’ll be able to pin down for certain how these ambitious performance figures will be achieved in the metal.